Process for producing solvents



Feb. 2, 1943. A L E, HARVEY, 1R v2,310,190

PRcEss FOR PRODUCING soLvENTs Filed July 13, 1940 Patented Feb. 2, 1943 31ans? PROCESS FOR PRODUCING SOLVENTS Jacquelin E. Harvey, Jr., Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia Application July 13, 1940, Serial No. 345,439

(Cl. 19t-57) 2 Claims.

This invention relates to the production of useful liquids from tars and fractions thereof. It relates more specifically to the catalytic production of solvents from tars and fractions thereof.

An object of the present invention is the production of solvents of aromatic nature.

A further obj ect of the present invention is the catalytic production of solvents of increased solvency from tars or fractions thereof, characterized by provision of maintaining said catalysis at optimum conditions, while reducing coke residue.

Other objects of the present invention will be apparent from the following disclosures.

Broadly viewed, the present process provides a method for converting tars, or fractions thereof substantially in entirety, if desired, into solvents ofv controllable boiling range, said conversion characterized by subjecting said tar, or fraction thereof, to the action of hydrogenwhile contacting a sulde catalyst, with catalysis being maintained at optimum conditions by specific provision. n

Theconversion of the starting tars of the present process to said solvents by the action of hy-` of, or aromatic -content serves as suitable starting material. l

Coal tar as a starting material contains such va high percentage of carbon that the solvents of the present invention, that is to say, solvent of increased solvency flowing from, among other things, increased boiling range of an intermediate parent material, are not produced in one step or cycle, but Aare rst depolymerized .by the actionoi:` hydrogen, to the end that when a deep cut, as hereinafter explained, is taken on the def polymerized tar, or fraction thereof, subsequently subjecting said deep cut to the action of a ow of hydrogensufficient to increase boiling range thereby increasing solvency, does not induce substantial carbonaceous increment.

The invention will'be understood from the following description of illustrative steps comprising various methods of securing the objects of the invention, when read in connection with the accompanying drawing wherein the gure is a diagrammatic sketch of an apparatus for carryingvout -a form-of the process of the invention and wherein the nature of the step carried out in each chamber and the contents thereof are indicated by legend.

The following examples will serve to, illustrate the present invention.

Example I.-A coal tar fraction boiling substantially` 3% at 380 C. was passed through aA high pressure reaction chamber in the presence of a molybdenum Asulfide catalyst, While flowing in 18,000 cubicy feet of hydrogen per barrel feed therewith. Temperature was 400 C. and pressure 300 atmospheres. Contact time was 1 hour. A test of the material under treatment after 8 hours showed 43% distilling at 380 C. After 32 hours the material distilled but 229 at the same temperature. Research disclosed that during the operation the sulfide catalyst, or at least a portion thereof, had changed to form other than sulfide. Research further disclosed that maintaining a hydrogen sulde partial pressure of at least a fractional atmosphere, aided in maintaining the catalyst in sulfide form, thus assisting in r. the depolymerizing step which forms an important part of the presentinvention. One-halfV 0f 1 percent sulphur was added to the feed stock and operation repeated. Other than normal aging of a the catalyst, the depolymerizing proceeded without substantial reduction to the end that in the order of 43%.was recoverable at 380 C., the hydrogenated mass being characterizedl by lowered specic gravity, coke residue, viscosity and solvency. n v

A fraction recovered to 380 C. was then subjected to the action of a flow of hydro-gen of less than 10,000 cubic lfeet per barrel feed stock, while contacting `a catalyst, at a temperature in excess of 400 C. and superatmospheric pressure and continued for such a length of time as to produce increased boiling points and induce solvency. The thus beneciated material was then fractionally4 distilled to recover Vsolvents of various boiling ranges with thefraction boiling 300 C. to 360 C. j serving as a *substitutefor conventional plasti v cizing oils., -v The point of fractionation may be made at one or. more points Vto recover substitutes, atleast in` boiling range, for any of the following:

` Degrees centigrade Benzol 78-120 Toluol 100-150 Hi-ash naphtha -200 Heavy naphtha 150-290 Plasticizers' 160-360 or others.

Some of the selected starting materials may contain suicient vinitial sulphur to maintain optimum catalyst activity. At times, recycle feeds need more sulphur addition to the end that the necessary hydrogen' sulfide atmosphereV be provided. The necessary hydrogen sulfide atmosphere is that atmosphere required to maintain at least a portion of the sulfide catalyst in substantial sulfide form and may be described as representing a partial pressure of at least a fractional atmosphere. For the maintenance of said hydrogen sulfide atmosphere, at times 1% sulphur, or more,vmay be added.

Regarding the removal of the lower boiling fractions from the depolymerized` starting material for subsequent increase-in boiling ranges by the action of hydrogen, as heretofore de-A scribed, said fractional removal may be made at any point whereby to provide, after further treatment, substitutes for any or all of the' noted solvents and plasticizers.

Example II.-A tar fraction boiling predominantly in excess of 220 C., and characterized by presence of high molecular complexes, is passed through a high pressure reaction vessel, in the presence of a tin sulfide Catalyst, while flowing 15,000 cubic feet of hydrogen per barrel feed; temperature 375 C. Pressure was 300 atmospheres and hydrogen sulfide partial pressure 11/2 atmospheres. Period of treatment was 1% hours, whereby to provide lowered specic gravity, viscosity, coke residue and solvency.

The thus beneficiated material was stripped of its low ends to 200 C. Said low ends were then subjected to the action of less than 8,000 cubic feet hydrogen per barrel feed at a temperature of 450 C. and a pressure in excess of 100 atmospheres. Catalyst was cobalt derivative and treatment continued for such a length of time as to increase boiling range and solvency.

For the hydrogen treating period characterized by solvency increase, the period may be very short, as for instance one minute, more or less, or several minutes, if desired; however, said period is selected to meetV process requirements, that isV to say, increase in solvency and boiling range.

Ensamble IH.A coal tar, specific gravity 1.1641, Conradson carbon 23 and 54.80% boiling above 380 C. was passed through a high pressure reaction chamber, in the presence of a vanadium sulfide catalyst, while flowing 20,000 cubic feet of hydrogen per barrel feed. Temperature was 410 C. and pressure 350 atmospheres; hydrogen sulfide partial pressure, 3A atmosphere. Time of treatment was 45 minutes, whereby to produced a depolymerized, or partially depolymerized product having lowered viscosity, specific gravity and solvency; resultant Conradson carbon, 10.3, specific gravity 1.0837, residue above 380 C., 44.5%.

The beneciated mass was then stripped of lower' ends to an upper limit of 290 C. Said lower ends were then subjected to a flow of hydrogen so controlled as to increase boiling range and solvency, said hydrogen flow being less than 6,000 cubic feet per barrel feed. Temperature, 460 C. Pressure, 225 atmospheres. Time so controlled as to provide said solvency increment.

When the term increased solvency is used herein, or in the appended claims is meant that the solvency when measured by usual standards, as for instance aniline point Aor Kauri-Butanol number, shows an improvement. 'Ihe term reduced or lowered solvency means the opposite of increased or enhanced solvency.

The hydrogen action of the present invention is so controlled that the coordinated pressure and .temperature selected produces no substantial carbonaceous deposition; other than such deposition as is inherent to the process and which usually results in plant shut down every 3 to 6 months or longer. Otherwise, the induced solvency of the present invention is not feasible of practice.

The action of hydrogen in the present invention may, therefore, be viewed as the controlled action that induces no substantial percentage of fractions not responsive to further hydrogenations, as for instance coke. Thus controls are exerted to the end that, if desired, in the order of upward of or more, are converted into the solvents of the present invention.

By the terms high molecular complexes, multiplicity of rings and ring multiples as used herein, and in the appended claims is meant those high boiling fractions especially susceptible to thermal degradation.

By the term beneciated as used is meant the starting material at least once subjected to the controlled action of hydrogen in accordance with the present process.

When the depolymerized starting material is stripped of its lower ends for further treatment by hydrogen, any selected portion of said stripped lower ends may comprise the starting material of the cycle characterized by increase in boiling points and solvency.

Instead of recovering the low boiling ends from the depolymerized starting material by distillation, said` recovery may, if desired, be effected by gas action.

By the term deep cut is meant that the cut so taken represents a predominant portion of the material cut. v

Hydrogen flows are usually in excess of 3,000 cubic feet per barrel of feed stock. In the two hydrogen cycles aforenamed, the hydrogen flow is coordinated with pressure and temperature to give, in the cycle characterized by depolymerization, a lowered solvency, whereas the secondcycle is characterized by increased solvency, and increased boiling points.

The catalyst of the present invention may originally be oxides which are converted, at least to a degree, to suldes in the presence of aforesaid hydrogen sulfide.

Hydrogen may be supplied as such, or gases ca pable of yielding hydrogen may be used. Diluting gas or gases may be used to control conversion, and for other purposes.

By the term depolymerize as used herein and in the appended claims, is meant, among other things, the reduction, including in sizeof aforesaid molecular complexes tothe end that they are not so susceptible to thermal degradation.

Residue resulting from distillation in the process may be used as an article of commerce, or recycled for further processing whereby to provide, if desired, additional solvent production.

The solvents of the present invention may be reiinedby alkalis, acids, solvents or further action of hydrogen.

All catalysts effective in the presence of hydrogen for aforementioned purposes are usable in conjunction with sulphide catalysts; as for instance, chromium, molybdenum, vanadium, uranium, cobalt, copper and their compounds, for

example sulfides or oxides; promoted `or not; with or without small amounts of alkali, acid or halid, or derivatives thereof; small amounts of halogen or halogens, as such, or incorporated with other substances; effective catalyst deposited on carriers, as for instance gels, earths, carbon, or the like; in various shapes, as for instance forms, ex-

truded shapes or lengths, pellets, comminuted; mixed with other material possessing desired action or not; with or Without other material effecting splitting or not; catalysts with added halogen derivatives.

In the conversion of the starting material, partially or approaching unity, into the solvents of the present process, temperatures of as low as 300 C. are usable; pressures of as low as 50 atmospheres may be used. However, temperatures and pressures of an increased range provide better commercial practice of the present invention. The time element is desirably that period that aords commercial recoveries of the products of, and incidental to, the present invention.

The term coal tar as used herein means a tar produced by the high temperature carbonizatio-n of coal, as for instance, high temperature coke oven tar or gas house tar.

Minor changes may be made in the steps of the process without departing from the spirit of the invention. In the claims axed to this specication no selection of any particular modication of the invention is intended to the exclusion of other modifications thereof.

I claim:

1. In the production of solvents from a mixture of high temperature coal tar fractions selected from the group consisting of coal tar, topped coal tar and coal tar fractions boiling preponderantly above 380 C., the process which comprises: subjecting said mixture of tar fractions at superatmospheric pressure to the action of a ow of hydrogen of at least about 15,000 cubic feet per barrel feed stock while contacting a sulfide catalyst vat a temperature chosen from the range above 400 C.; maintaining a hydrogen sulde partial pressure selected between the lirnits of about three quarter atmosphere to one and one-half atmospheres; continuing the treatment for such a length of time as to lower specic gravity, coke residue and viscosity; stripping the beneiiciated material to provide an intermediate starting material having an end point selected between the range of 200 C. and 380 C.; subj ecting said intermediate starting material to the action of a iiow of hydrogen selected between the limits of about 3,000-6,000 cubic feet per barrel 

